This invention relates generally to insulated windows and particularly to an insulated window panel assembly and a spacer for use in such a panel assembly, including a method for making the spacer and the window panel assembly.
Insulated windows typically include two or more panes of glass spaced from each other and mounted in a sash or other opening (FIG. 1). In early embodiments, the window panes were separated by blocks or strips of wood, cut to length, and fixed in the window opening. Alternatively, the window panes were received in rabbits or recesses formed in the sash and sealed therewith by a bead of adhesive about the window opening. Disadvantages of these structures include the relatively high cost in time and materials and the inability to insure an airtight space between the window panes.
In later insulated windows, the separated panes were assembled as a unit separate from the window opening or sash. The window panes were separated from each other by a plurality of rectangular or square lengths of metal tubing, interconnected at the ends by angled corner keys (FIG. 2). Each segment was cut to length and interconnected by the corner keys. The airtight integrity of the gap between the panes was provided by wrapping the joints between the corner keys and the segments of tubing with a seal. Additionally, each segment may have been filled with a desiccant. The gap or insulative space between the panes may also have been evacuated and refilled with a gas, such as Argon, to reduce conduction and heat transfer. However, as a result of the many joints, the Argon gas often escaped, despite the fact that a second seal often surrounded the entire perimeter of the space between the two window panes.
Another spacer used by most insulated window manufacturers includes a length of rectangular or square metal tubing (FIG. 3) bent about a mandrel (FIGS. 4A, 4B, 4C, and 4D) to form a pattern substantially conforming to the shape of the window panes. Bulging of the sides of the tubing at a bend is constrained by clamps located on each side of the bend (FIGS. 4A-4D) to maintain a uniform thickness of the spacer. A disadvantage of this construction is the need for the clamp and mandrel. If the sides are not constrained, the sides deform outwardly, forming projections which form a stress point on the surface of the glass panes, increasing the probability of a stress failure of the glass pane(s). Bending the spacer using the mandrel requires the side restraining clamps to avoid the stress points. Such a procedure results in slower production or increased capital expenditures for work-specific machines.
The instant invention provides a unique tubular spacer for insulated window panel assemblies which can be bent without mandrels or corner restraining clamps to produce angled spacers having uniform thickness and all of the advantages of a single, continuous spacer, including better sealing of an inert gas between the panes, ease of construction, and reduced costs.